1. Field of the Invention
The present invention relates to an actuator that causes deformation when a voltage is applied across electrodes, and particularly, to a polymer actuator that causes deformation in accordance with ion transfer resulting from an electric field.
2. Description of the Related Art
For some time, an ion conducting actuator has been known as one of polymer actuators, where the ion conducting actuator includes an ion-exchange resin layer and metallic electrode layers formed on surfaces of the ion-exchange resin layer so as to be electrically insulated from each other (for example, refer to Japanese Unexamined Patent Application Publication No. 235064). The polymer actuator functions as an actuator by applying a voltage across the metallic electrode layers so that the ion-exchange resin layer is deformed to be curved.
Further, an actuator using a gel having an ion liquid and a carbon nanotube as an electrode layer has been known (for example, refer to Japanese Unexamined Patent Application Publication No. 2005-176428).
FIG. 6 shows a state where upper and lower surfaces of electrodes 3 and 3 constituting a polymer actuator 1 shown in FIG. 5 are sandwiched by connection portions 4a of base substrates 4 so as to fix and support the end portion of the polymer actuator 1.
However, when a strong pressure is applied to the polymer actuator 1 in the thickness direction by sandwiching the polymer actuator 1 using the base substrates 4, the electrode 3 and the electrolyte layer 2 are crushed so that the gap T1 between the electrodes 3 and 3 becomes small since the polymer actuator 1 is formed of a smooth material. Since the electric field strength of the support portion having a decreased gap becomes higher than that of the displacement portion, the concentration of ion transfer more easily occurs in the support portion. As a result, a problem arises in that the displacement amount or the driving force with the displacement is reduced. Further, the insulation performance may be easily degraded due to a decrease in the gap T1. Accordingly, steady current leakage increases, power consumption increases, and a curved displacement amount and a driving force with the curved displacement decrease, which causes a problem in that the characteristics of the actuator are degraded.